Halep, the top seed in the tournament, won the Shenzhen Open title on Sunday but was not fully healthy.

"During the tournament in China I got this problem in my stomach," explained Halep. "I was waiting until today to see if I was ready to play again, but I feel like I cannot play. It's tough to play a tournament like this, so unfortunately I decided to withdraw."

Halep, a runner-up at last year's French Open, is expected to be ready for the Australian Open, which starts next week.

Nicole Gibbs took Halep's spot in the tournament as a lucky loser and was whitewashed by Karolina Pliskova, 6-0, 6-0, in just 38 minutes.